This invention relates to a device for manipulation of liquids and a process for producing and using such a device.
Document WO 02/085520 A2 discloses a body which has a surface which has first and second surface areas which have different wettability with a liquid. The surface areas can, for example, be hydrophilic on the one hand and hydrophobic on the other hand. It is possible for the surface areas to be lipophilic or lipophobic with respect to oily solutions. In this publication, two processes for producing different surface areas are named. Thus, on the one hand the different wetting properties can be achieved by coatings. These coatings can be attained by lithographic processes with subsequent coating steps. On the other hand, the different wetting properties can be attained by microstructuring, as is the case in the so-called lotus effect which is based on different roughnesses of the surface. These different roughnesses can be obtained by microstructuring of the corresponding surface areas. Within the microstructured areas, capillary forces act which keep the liquids in these surface areas. The publication, as an example for producing a microstructure, names a chemical treatment, or ion irradiation.
If microstructuring is produced by chemical treatment, etching is possible, or by ion irradiation, an irregularly structured surface is formed in the generic solids. The surface cannot be exactly acquired by computations.
Therefore, it is difficult to exactly specify the acting capillary forces. But if surface areas with different capillary forces are to be produced, it is advantageous to know exactly the acting capillary forces of each surface area and to produce surface areas with desired capillary forces.
Another problem with the microstructures produced by the known processes is that the acting capillary forces which keep the liquid in one of the surface areas and which thus also dictate the amounts of liquid which can be stored in the surface area are relatively small. Thus only a relatively small amount of liquid can be deposited in the microstructured surface area.
The publication, with the publication number U.S. Pat. No. 6,451,264 B1, discloses a device with which liquids are routed through curved capillary channels to different chambers in which the liquid can be tested for certain reactions. In the device, there are dry reagents which are suitable for this purpose. The dry reagents should be located in the chambers in which the liquid is tested.
In the curved capillary channels, the phenomenon occurs that the liquid on the wall with the smaller radius is conveyed more rapidly than the opposing channel wall with the larger radius. Uniform motion of the liquid through the curved channels is therefore conventionally not possible. In order to remedy this problem, in the indicated publication, it is proposed that microstructured surfaces with regularly arranged structure elements be placed in the curved channel; these elements ensure uniform motion of the liquid in the curved channels. If a liquid reaches such a microstructured surface area in the curved channel, first this microstructured surface area is filled with liquid. Only when the microstructured surface area is completely filled with liquid do the transport forces cause the liquid in the transport direction to emerge again from the microstructured surface area. Transport along the channel wall with the smaller radius which is more rapid than the transport of the liquid along the channel wall with the larger radius is thus prevented. The liquid is transported uniformly through the curved channel.
The microstructured surface areas in the curved channels of the device, according to the indicated publication, are thus not suited or intended for storing or depositing a liquid. The purpose of the microstructured surface areas is to ensure uniform motion of the liquid in the curved channel. The device, as is known from the publication with the publication number U.S. Pat. No. 6,451,264 B1, is not suited for manipulation of liquids in the sense of this invention, especially not for storage or deposition of defined amounts of liquid.
The document, with publication number U.S. Pat. No. 6,368,871 B1, discloses a device which has a surface area in which microstructure elements are located. This surface extends in a widened point of a channel from the one channel wall to the opposing channel wall. The structures are used to filter a certain substance out of the liquid flowing through the channel in order to extract or concentrate it (column 7, line 40 to line 57). The microstructure elements of the surface area in the channel are neither suited nor intended to store or deposit defined amounts of liquid. Nor is storage of defined amounts of reagents in the surface areas known.
A device for manipulation of liquids has a solid. This solid has, as is already known, surface areas in which different capillary forces are acting. One or more first surface areas have a microstructured and/or nanostructured surface which have regularly arranged structure elements. The structure elements are connected in one piece to the remaining solid and consist of the same material as the remaining solid.
The regularly arranged structure elements in the first surface area, or in the first surface areas, produce capillary forces which provide for the liquid's remaining in the first surface area. The action of the capillary forces is so great that the liquid which touches the edge of the first surface area is sucked into the first surface area by the capillary force. By the choice and the configuration of the structure elements in the first surface area, the capillary force caused by the structure elements can be set. Setting can take place by trying out various geometries or by concerted calculation of the capillary force of the geometries. The defined capillary force of the first surface areas makes it possible to store or deposit a defined amount of liquid in the first surface areas. Thus, for example, defined amounts of one or different reagent liquids can be deposited and immobilized in the surface areas, for example dried up. This ensures that a defined amount of the reagent is located in the first surface area. Later a second amount of liquid, for example, a sample liquid, can be delivered onto the first surface area, this second amount of liquid also being limited, i.e. being defined, by the known capillary force of the first surface area.
One or more first surface areas can be provided with one or different agents. The reagents can be stored between the structure elements. Furthermore, it is possible for the reagents to be encapsulated in particles, these particles being plastic particles or magnetic particles. Likewise, it is possible for the second surface areas to be provided with reagents.
The reagent or the reagents can be stored in a resuspendable manner in the first surface area or areas. To do this, the reagents can be moved in liquid form by means of a pipette onto the first surface areas of the device. Then the reagents are dried up. The reagents are not covalently coupled to the surface, but can be resuspended over suitable liquids.
The reagents can then be resuspended, for example, by a sample (liquid material for analysis). To do this, the sample can be moved directly onto the first surface areas or can be routed via a channel system, especially via a channel system of capillary channels, to the first surface areas from an inlet. The reagents are dissolved and mobilized by contact with the sample. In this way, they can react with the sample. The reagents which have been dried up in the first surface area and which are also called dry chemicals or dry reagents because of this drying up, can be suited to detection of a certain component of the sample. The dry chemicals can be used to make the components of the sample visible. This can take place by simple dyeing or by conventional enzymatic chemoluminometric indicator reactions. The reaction can then be analyzed, for example, by photometric studies or with the naked eye. In addition to the indicated optical processes, electrochemical analysis processes can also be used, for example, by electrodes in the device.
The reagents can also be permanently stored in the first surface areas of a device as described in the invention. The reagents can then be used as biochemical probes, the substance present in a sample liquid which has been dispensed onto the first surface areas being bound in a concerted manner to these biochemical probes; this enables detection of the substance. The reagents stored permanently in the first surface areas are not resuspended by the sample liquid. The reagents are inserted rather securely in the surface of the first surface areas. The substances which are present in the sample liquid react with these stored reagents. The reaction product cannot be washed out. Rather the reaction product must be examined at the location of the first surface areas, for example, by optical processes.
A device as claimed in the invention can be produced for example by the following process. First, in the surface of the solid, surface areas are produced by working (for example, metal cutting, laser working or ion beam working) of the solid, in the surface areas at least partially different capillary forces acting. In the first surface areas during working microstructured and/or nanostructured surfaces are produced and are formed by regularly arranged structure elements. Likewise, it is possible to mold the microstructures of the first surface areas in the production of the solid, for example, by injection molding (microinjection molding) into the surface of the solid. A solid then advantageously consist of a plastic. But it is also possible to produce the solid of a device from glass or silicon.
In the device, there can be second surface areas which are made preferably flat, i.e. without microstructuring or nanostructuring. In the second surface areas preferably compared to the first surface areas in any case low capillary forces are acting so that a liquid is preferably stored in the first surface areas or is preferably taken up by the first surface areas.
In the first surface areas of a device capillary forces of different size can act.
The structure elements of a device which are intended for microstructuring and/or nanostructuring of the first surface areas can comprise columns and/or stelae. These columns can have a diameter from 0.1 to 500 microns. The distance from column or stele to column or stele can be 0.1 to 500 microns.
The columns or stelae can have a circular or polygonal cross section. The diameter of the columns or stelae is advantageously 0.1 to 500 microns.
The structure elements can furthermore comprise grooves which preferably have a width from 0.1 to 500 microns and a depth from 0.1 to 500 microns. The grooves are preferably arranged in parallel, have a distance from 0.1 to 500 microns from one another and are preferably 0.1 to 500 microns deep. The grooves can be straight or circular. It is possible for the grooves to have a notch-like cross section. The grooves can be joined to one another and form a channel structure, for example, a net-like or meandering channel structure.
Moreover, it is possible for there to be crosspieces as structure elements in the device. These crosspieces can have a width from 0.1 to 500 microns and a height from 0.1 to 500 microns. Advantageously, the crosspieces have a distance from 0.1 to 500 microns and are arranged in parallel to one another.
In a lowered first surface area, the structure elements can also be notches which are made in the edge of the lowered surface area. These notches are, for example, known from document U.S. Pat. No. 6,296,126 B1, FIG. 6, reference number 17 as means for overcoming a capillary stop.
In the device, one or more first surface areas are lowered or elevated relative to the surrounding surface. Such a sudden change of the surface properties and the resulting large capillary force, similarly to a capillary stop, lead to a capillary jump which clearly delimits the elevated or lowered surface areas.
The first surface areas can be arranged in the form of a matrix, the first surface areas being surrounded in part or preferably completely by the second surface area. The first surface areas can be located especially also in a chamber of the device which has an inlet and an outlet so that a sample liquid can flow through the chamber. The first surface areas can then be located both next to one another and also in succession in one or more rows in the chamber, each first surface area being surrounded by the second surface area.
The first surface areas of a device can be functionalized before applying the reagents by plasma processes such as, for example, plasma polymerization or wet chemical processes. In this way, the amount of reagent which is to be stored in the first surface area can be increased.
In one preferred version of a device, one section of the continuous first and/or second surface areas is lowered relative to the surrounding surface. This continuous section can then be closed with a cover, and the cover can be formed by a second solid which can be made like the first solid, and the space located between the section and the cover forming a reaction chamber. If the second solid is made similarly to the first solid, it preferably has first surface areas which are located advantageously opposite to the first surface areas of the first solid.
Such a device can then have a first inlet. This inlet then advantageously comprises an inlet channel which discharges into the reaction chamber, an inlet chamber and/or an inlet opening in the cover or in the solid. The inlet can also discharge directly into the first surface area.
Analogously there can also be an outlet in the device. This outlet can comprise an outlet channel which begins in the reaction chamber and which advantageously adjoins an outlet chamber. This outlet chamber can then be connected to the environment via an outlet opening in the cover or in the solid.
The inlet and the outlet of a device as claimed in the invention are used on the one hand to add and remove the sample liquid. On the other hand the inlet and the outlet are also used for aeration and deaeration during transport processes in a device and especially in its reaction chamber.
In a device, there can be one or more second inlets. These second inlets, analogously to the first inlets, are equipped advantageously with inlet channels, inlet chambers, and/or inlet openings in the cover or in the solid. The inlet channels are then joined to one first surface area at a time. But it is also conceivable for the inlet channels of the second inlets to be connected to a second surface area.
In the process, after producing the first surface areas in the solid, a reagent-containing liquid can be dispensed onto the first surface areas. Different liquids can be dispensed onto different first surface areas. These liquids can then be mixed with another liquid, specifically a sample, the sample reacting with the reagents. It is possible for the reagents to be temporarily attached, for example, dried up, to the first surfaces. The reagents are then stored as a solid on the surfaces. By supplying a sample these dried-up reagents can then be dissolved. The sample then reacts with the dissolved reagents in the area of the first surface areas, on a separate reaction chamber of the device or after removal from the device outside the device. Furthermore, it is also possible for the dried-up reagents to be dissolved with a solvent in order then in the area of the first surface areas or in another area of the device to be mixed with a sample liquid in order to initiate the desired reaction.
It is possible for the reagents to be permanently attached in the first surface areas, i.e. immobilized. The reagents can be attached via a covalent bond. The sample can then be delivered onto the first surface areas for analysis. If then the substance which is to be analyzed should be present in the sample, it binds to the corresponding first surface areas. This binding reaction can be detected via a corresponding indicator reaction.
The microstructured or nanostructured surfaces of the first surface areas can be shaped in a depression of the solid. If this depression is closed with a cover, the depression forms a reaction chamber. Advantageously, there is a first inlet for this reaction chamber. Furthermore, there can also be a second inlet which is closed when a liquid with reagents is added to the device. The closing of the second inlet has the advantage that in this way the amount of liquid exactly metered with the reagents can be delivered into the device or into the reaction chamber in order to isolate it subsequently from the environment.